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rocksdb/db/memtable_list.cc
Abhishek Madan 8fe1e06ca0 Clean up FragmentedRangeTombstoneList (#4692) 
Summary:
Removed `one_time_use` flag, which removed the need for some
tests, and changed all `NewRangeTombstoneIterator` methods to return
`FragmentedRangeTombstoneIterators`.

These changes also led to removing `RangeDelAggregatorV2::AddUnfragmentedTombstones`
and one of the `MemTableListVersion::AddRangeTombstoneIterators` methods.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4692

Differential Revision: D13106570

Pulled By: abhimadan

fbshipit-source-id: cbab5432d7fc2d9cdfd8d9d40361a1bffaa8f845
2018-11-28 15:29:02 -08:00

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
#include "db/memtable_list.h"
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <inttypes.h>
#include <limits>
#include <queue>
#include <string>
#include "db/db_impl.h"
#include "db/memtable.h"
#include "db/range_tombstone_fragmenter.h"
#include "db/version_set.h"
#include "monitoring/thread_status_util.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "rocksdb/iterator.h"
#include "table/merging_iterator.h"
#include "util/coding.h"
#include "util/log_buffer.h"
#include "util/sync_point.h"
namespace rocksdb {
class InternalKeyComparator;
class Mutex;
class VersionSet;
void MemTableListVersion::AddMemTable(MemTable* m) {
memlist_.push_front(m);
*parent_memtable_list_memory_usage_ += m->ApproximateMemoryUsage();
}
void MemTableListVersion::UnrefMemTable(autovector<MemTable*>* to_delete,
MemTable* m) {
if (m->Unref()) {
to_delete->push_back(m);
assert(*parent_memtable_list_memory_usage_ >= m->ApproximateMemoryUsage());
*parent_memtable_list_memory_usage_ -= m->ApproximateMemoryUsage();
}
}
MemTableListVersion::MemTableListVersion(
size_t* parent_memtable_list_memory_usage, MemTableListVersion* old)
: max_write_buffer_number_to_maintain_(
old->max_write_buffer_number_to_maintain_),
parent_memtable_list_memory_usage_(parent_memtable_list_memory_usage) {
if (old != nullptr) {
memlist_ = old->memlist_;
for (auto& m : memlist_) {
m->Ref();
}
memlist_history_ = old->memlist_history_;
for (auto& m : memlist_history_) {
m->Ref();
}
}
}
MemTableListVersion::MemTableListVersion(
size_t* parent_memtable_list_memory_usage,
int max_write_buffer_number_to_maintain)
: max_write_buffer_number_to_maintain_(max_write_buffer_number_to_maintain),
parent_memtable_list_memory_usage_(parent_memtable_list_memory_usage) {}
void MemTableListVersion::Ref() { ++refs_; }
// called by superversion::clean()
void MemTableListVersion::Unref(autovector<MemTable*>* to_delete) {
assert(refs_ >= 1);
--refs_;
if (refs_ == 0) {
// if to_delete is equal to nullptr it means we're confident
// that refs_ will not be zero
assert(to_delete != nullptr);
for (const auto& m : memlist_) {
UnrefMemTable(to_delete, m);
}
for (const auto& m : memlist_history_) {
UnrefMemTable(to_delete, m);
}
delete this;
}
}
int MemTableList::NumNotFlushed() const {
int size = static_cast<int>(current_->memlist_.size());
assert(num_flush_not_started_ <= size);
return size;
}
int MemTableList::NumFlushed() const {
return static_cast<int>(current_->memlist_history_.size());
}
// Search all the memtables starting from the most recent one.
// Return the most recent value found, if any.
// Operands stores the list of merge operations to apply, so far.
bool MemTableListVersion::Get(const LookupKey& key, std::string* value,
Status* s, MergeContext* merge_context,
SequenceNumber* max_covering_tombstone_seq,
SequenceNumber* seq, const ReadOptions& read_opts,
ReadCallback* callback, bool* is_blob_index) {
return GetFromList(&memlist_, key, value, s, merge_context,
max_covering_tombstone_seq, seq, read_opts, callback,
is_blob_index);
}
bool MemTableListVersion::GetFromHistory(
const LookupKey& key, std::string* value, Status* s,
MergeContext* merge_context, SequenceNumber* max_covering_tombstone_seq,
SequenceNumber* seq, const ReadOptions& read_opts, bool* is_blob_index) {
return GetFromList(&memlist_history_, key, value, s, merge_context,
max_covering_tombstone_seq, seq, read_opts,
nullptr /*read_callback*/, is_blob_index);
}
bool MemTableListVersion::GetFromList(
std::list<MemTable*>* list, const LookupKey& key, std::string* value,
Status* s, MergeContext* merge_context,
SequenceNumber* max_covering_tombstone_seq, SequenceNumber* seq,
const ReadOptions& read_opts, ReadCallback* callback, bool* is_blob_index) {
*seq = kMaxSequenceNumber;
for (auto& memtable : *list) {
SequenceNumber current_seq = kMaxSequenceNumber;
bool done =
memtable->Get(key, value, s, merge_context, max_covering_tombstone_seq,
&current_seq, read_opts, callback, is_blob_index);
if (*seq == kMaxSequenceNumber) {
// Store the most recent sequence number of any operation on this key.
// Since we only care about the most recent change, we only need to
// return the first operation found when searching memtables in
// reverse-chronological order.
// current_seq would be equal to kMaxSequenceNumber if the value was to be
// skipped. This allows seq to be assigned again when the next value is
// read.
*seq = current_seq;
}
if (done) {
assert(*seq != kMaxSequenceNumber || s->IsNotFound());
return true;
}
if (!done && !s->ok() && !s->IsMergeInProgress() && !s->IsNotFound()) {
return false;
}
}
return false;
}
Status MemTableListVersion::AddRangeTombstoneIterators(
const ReadOptions& read_opts, Arena* /*arena*/,
RangeDelAggregatorV2* range_del_agg) {
assert(range_del_agg != nullptr);
for (auto& m : memlist_) {
// Using kMaxSequenceNumber is OK because these are immutable memtables.
std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
m->NewRangeTombstoneIterator(read_opts,
kMaxSequenceNumber /* read_seq */));
range_del_agg->AddTombstones(std::move(range_del_iter));
}
return Status::OK();
}
void MemTableListVersion::AddIterators(
const ReadOptions& options, std::vector<InternalIterator*>* iterator_list,
Arena* arena) {
for (auto& m : memlist_) {
iterator_list->push_back(m->NewIterator(options, arena));
}
}
void MemTableListVersion::AddIterators(
const ReadOptions& options, MergeIteratorBuilder* merge_iter_builder) {
for (auto& m : memlist_) {
merge_iter_builder->AddIterator(
m->NewIterator(options, merge_iter_builder->GetArena()));
}
}
uint64_t MemTableListVersion::GetTotalNumEntries() const {
uint64_t total_num = 0;
for (auto& m : memlist_) {
total_num += m->num_entries();
}
return total_num;
}
MemTable::MemTableStats MemTableListVersion::ApproximateStats(
const Slice& start_ikey, const Slice& end_ikey) {
MemTable::MemTableStats total_stats = {0, 0};
for (auto& m : memlist_) {
auto mStats = m->ApproximateStats(start_ikey, end_ikey);
total_stats.size += mStats.size;
total_stats.count += mStats.count;
}
return total_stats;
}
uint64_t MemTableListVersion::GetTotalNumDeletes() const {
uint64_t total_num = 0;
for (auto& m : memlist_) {
total_num += m->num_deletes();
}
return total_num;
}
SequenceNumber MemTableListVersion::GetEarliestSequenceNumber(
bool include_history) const {
if (include_history && !memlist_history_.empty()) {
return memlist_history_.back()->GetEarliestSequenceNumber();
} else if (!memlist_.empty()) {
return memlist_.back()->GetEarliestSequenceNumber();
} else {
return kMaxSequenceNumber;
}
}
// caller is responsible for referencing m
void MemTableListVersion::Add(MemTable* m, autovector<MemTable*>* to_delete) {
assert(refs_ == 1); // only when refs_ == 1 is MemTableListVersion mutable
AddMemTable(m);
TrimHistory(to_delete);
}
// Removes m from list of memtables not flushed. Caller should NOT Unref m.
void MemTableListVersion::Remove(MemTable* m,
autovector<MemTable*>* to_delete) {
assert(refs_ == 1); // only when refs_ == 1 is MemTableListVersion mutable
memlist_.remove(m);
m->MarkFlushed();
if (max_write_buffer_number_to_maintain_ > 0) {
memlist_history_.push_front(m);
TrimHistory(to_delete);
} else {
UnrefMemTable(to_delete, m);
}
}
// Make sure we don't use up too much space in history
void MemTableListVersion::TrimHistory(autovector<MemTable*>* to_delete) {
while (memlist_.size() + memlist_history_.size() >
static_cast<size_t>(max_write_buffer_number_to_maintain_) &&
!memlist_history_.empty()) {
MemTable* x = memlist_history_.back();
memlist_history_.pop_back();
UnrefMemTable(to_delete, x);
}
}
// Try to record multiple successful flush to the MANIFEST as an atomic unit.
// This function may just return Status::OK if there has already been
// a concurrent thread performing actual recording.
Status MemTableList::TryInstallMemtableFlushResults(
autovector<MemTableList*>& imm_lists,
const autovector<ColumnFamilyData*>& cfds,
const autovector<const MutableCFOptions*>& mutable_cf_options_list,
const autovector<const autovector<MemTable*>*>& mems_list,
bool* atomic_flush_commit_in_progress, LogsWithPrepTracker* prep_tracker,
VersionSet* vset, InstrumentedMutex* mu,
const autovector<FileMetaData>& file_metas,
autovector<MemTable*>* to_delete, Directory* db_directory,
LogBuffer* log_buffer) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_MEMTABLE_INSTALL_FLUSH_RESULTS);
mu->AssertHeld();
for (size_t k = 0; k != mems_list.size(); ++k) {
for (size_t i = 0; i != mems_list[k]->size(); ++i) {
assert(i == 0 || (*mems_list[k])[i]->GetEdits()->NumEntries() == 0);
(*mems_list[k])[i]->flush_completed_ = true;
(*mems_list[k])[i]->file_number_ = file_metas[k].fd.GetNumber();
}
}
assert(atomic_flush_commit_in_progress != nullptr);
Status s;
if (*atomic_flush_commit_in_progress) {
// If the function reaches here, there must be a concurrent thread that
// have already started recording to MANIFEST. Therefore we should just
// return Status::OK and let the othe thread finish writing to MANIFEST on
// our behalf.
return s;
}
// If the function reaches here, the current thread will start writing to
// MANIFEST. It may record to MANIFEST the flush results of other flushes.
*atomic_flush_commit_in_progress = true;
auto comp = [&imm_lists](size_t lh, size_t rh) {
const auto& memlist1 = imm_lists[lh]->current_->memlist_;
const auto& memlist2 = imm_lists[rh]->current_->memlist_;
auto it1 = memlist1.rbegin();
auto it2 = memlist2.rbegin();
return (*it1)->atomic_flush_seqno_ > (*it2)->atomic_flush_seqno_;
};
// The top of the heap is the memtable with smallest atomic_flush_seqno_.
std::priority_queue<size_t, std::vector<size_t>, decltype(comp)> heap(comp);
// Sequence number of the oldest unfinished atomic flush.
SequenceNumber min_unfinished_seqno = kMaxSequenceNumber;
// Populate the heap with first element of each imm iff. it has been
// flushed to storage, i.e. flush_completed_ is true.
size_t num = imm_lists.size();
assert(num == cfds.size());
for (size_t i = 0; i != num; ++i) {
std::list<MemTable*>& memlist = imm_lists[i]->current_->memlist_;
if (memlist.empty()) {
continue;
}
auto it = memlist.rbegin();
if ((*it)->flush_completed_) {
heap.emplace(i);
} else if (min_unfinished_seqno > (*it)->atomic_flush_seqno_) {
min_unfinished_seqno = (*it)->atomic_flush_seqno_;
}
}
while (s.ok() && !heap.empty()) {
autovector<size_t> batch;
SequenceNumber seqno = kMaxSequenceNumber;
// Pop from the heap the memtables that belong to the same atomic flush,
// namely their atomic_flush_seqno_ are equal.
do {
size_t pos = heap.top();
const auto& memlist = imm_lists[pos]->current_->memlist_;
MemTable* mem = *(memlist.rbegin());
if (seqno == kMaxSequenceNumber) {
// First mem in this batch.
seqno = mem->atomic_flush_seqno_;
batch.emplace_back(pos);
heap.pop();
} else if (mem->atomic_flush_seqno_ == seqno) {
// mem has the same atomic_flush_seqno_, thus in the same atomic flush.
batch.emplace_back(pos);
heap.pop();
} else if (mem->atomic_flush_seqno_ > seqno) {
// mem belongs to another atomic flush with higher seqno, break the
// loop.
break;
}
} while (!heap.empty());
if (seqno >= min_unfinished_seqno) {
// If there is an older, unfinished atomic flush, then we should not
// proceed.
TEST_SYNC_POINT_CALLBACK(
"MemTableList::TryInstallMemtableFlushResults:"
"HasOlderUnfinishedAtomicFlush:0",
nullptr);
break;
}
// Found the earliest, complete atomic flush. No earlier atomic flush is
// pending. Therefore ready to record it to the MANIFEST.
uint32_t num_entries = 0;
autovector<ColumnFamilyData*> tmp_cfds;
autovector<const MutableCFOptions*> tmp_mutable_cf_options_list;
std::vector<autovector<MemTable*>> memtables_to_flush;
autovector<autovector<VersionEdit*>> edit_lists;
for (auto pos : batch) {
tmp_cfds.emplace_back(cfds[pos]);
tmp_mutable_cf_options_list.emplace_back(mutable_cf_options_list[pos]);
const auto& memlist = imm_lists[pos]->current_->memlist_;
uint64_t batch_file_number = 0;
autovector<MemTable*> tmp_mems;
autovector<VersionEdit*> edits;
for (auto it = memlist.rbegin(); it != memlist.rend(); ++it) {
MemTable* m = *it;
if (!m->flush_completed_ ||
(it != memlist.rbegin() && m->file_number_ != batch_file_number)) {
break;
}
if (it == memlist.rbegin()) {
batch_file_number = m->file_number_;
edits.push_back(m->GetEdits());
++num_entries;
}
tmp_mems.push_back(m);
}
edit_lists.push_back(edits);
memtables_to_flush.push_back(tmp_mems);
}
TEST_SYNC_POINT_CALLBACK(
"MemTableList::TryInstallMemtableFlushResults:FoundBatchToCommit:0",
&num_entries);
// Mark the version edits as an atomic group
uint32_t remaining = num_entries;
for (auto& edit_list : edit_lists) {
assert(edit_list.size() == 1);
edit_list[0]->MarkAtomicGroup(--remaining);
}
assert(remaining == 0);
size_t batch_sz = batch.size();
assert(batch_sz > 0);
assert(batch_sz == memtables_to_flush.size());
assert(batch_sz == tmp_cfds.size());
assert(batch_sz == edit_lists.size());
if (vset->db_options()->allow_2pc) {
for (size_t i = 0; i != batch_sz; ++i) {
auto& edit_list = edit_lists[i];
assert(!edit_list.empty());
edit_list.back()->SetMinLogNumberToKeep(
PrecomputeMinLogNumberToKeep(vset, *tmp_cfds[i], edit_list,
memtables_to_flush[i], prep_tracker));
}
}
// this can release and reacquire the mutex.
s = vset->LogAndApply(tmp_cfds, tmp_mutable_cf_options_list, edit_lists, mu,
db_directory);
for (const auto pos : batch) {
imm_lists[pos]->InstallNewVersion();
}
if (s.ok()) {
for (size_t i = 0; i != batch_sz; ++i) {
if (tmp_cfds[i]->IsDropped()) {
continue;
}
size_t pos = batch[i];
for (auto m : memtables_to_flush[i]) {
assert(m->file_number_ > 0);
uint64_t mem_id = m->GetID();
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit table #%" PRIu64
": memtable #%" PRIu64 " done",
tmp_cfds[i]->GetName().c_str(), m->file_number_,
mem_id);
imm_lists[pos]->current_->Remove(m, to_delete);
}
}
} else {
for (size_t i = 0; i != batch_sz; ++i) {
size_t pos = batch[i];
for (auto m : memtables_to_flush[i]) {
uint64_t mem_id = m->GetID();
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit table #%" PRIu64
": memtable #%" PRIu64 " failed",
tmp_cfds[i]->GetName().c_str(), m->file_number_,
mem_id);
m->flush_completed_ = false;
m->flush_in_progress_ = false;
m->edit_.Clear();
m->file_number_ = 0;
imm_lists[pos]->num_flush_not_started_++;
}
imm_lists[pos]->imm_flush_needed.store(true, std::memory_order_release);
}
}
// Adjust the heap AFTER installing new MemTableListVersions because the
// compare function 'comp' needs to capture the most up-to-date state of
// imm_lists.
for (auto pos : batch) {
const auto& memlist = imm_lists[pos]->current_->memlist_;
if (!memlist.empty()) {
MemTable* mem = *(memlist.rbegin());
if (mem->flush_completed_) {
heap.emplace(pos);
} else if (min_unfinished_seqno > mem->atomic_flush_seqno_) {
min_unfinished_seqno = mem->atomic_flush_seqno_;
}
}
}
}
*atomic_flush_commit_in_progress = false;
return s;
}
// Returns true if there is at least one memtable on which flush has
// not yet started.
bool MemTableList::IsFlushPending() const {
if ((flush_requested_ && num_flush_not_started_ > 0) ||
(num_flush_not_started_ >= min_write_buffer_number_to_merge_)) {
assert(imm_flush_needed.load(std::memory_order_relaxed));
return true;
}
return false;
}
// Returns the memtables that need to be flushed.
void MemTableList::PickMemtablesToFlush(const uint64_t* max_memtable_id,
autovector<MemTable*>* ret) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_PICK_MEMTABLES_TO_FLUSH);
const auto& memlist = current_->memlist_;
for (auto it = memlist.rbegin(); it != memlist.rend(); ++it) {
MemTable* m = *it;
if (max_memtable_id != nullptr && m->GetID() > *max_memtable_id) {
break;
}
if (!m->flush_in_progress_) {
assert(!m->flush_completed_);
num_flush_not_started_--;
if (num_flush_not_started_ == 0) {
imm_flush_needed.store(false, std::memory_order_release);
}
m->flush_in_progress_ = true; // flushing will start very soon
ret->push_back(m);
}
}
flush_requested_ = false; // start-flush request is complete
}
void MemTableList::RollbackMemtableFlush(const autovector<MemTable*>& mems,
uint64_t /*file_number*/) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_MEMTABLE_ROLLBACK);
assert(!mems.empty());
// If the flush was not successful, then just reset state.
// Maybe a succeeding attempt to flush will be successful.
for (MemTable* m : mems) {
assert(m->flush_in_progress_);
assert(m->file_number_ == 0);
m->flush_in_progress_ = false;
m->flush_completed_ = false;
m->edit_.Clear();
num_flush_not_started_++;
}
imm_flush_needed.store(true, std::memory_order_release);
}
// Try record a successful flush in the manifest file. It might just return
// Status::OK letting a concurrent flush to do actual the recording..
Status MemTableList::TryInstallMemtableFlushResults(
ColumnFamilyData* cfd, const MutableCFOptions& mutable_cf_options,
const autovector<MemTable*>& mems, LogsWithPrepTracker* prep_tracker,
VersionSet* vset, InstrumentedMutex* mu, uint64_t file_number,
autovector<MemTable*>* to_delete, Directory* db_directory,
LogBuffer* log_buffer) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_MEMTABLE_INSTALL_FLUSH_RESULTS);
mu->AssertHeld();
// Flush was successful
// Record the status on the memtable object. Either this call or a call by a
// concurrent flush thread will read the status and write it to manifest.
for (size_t i = 0; i < mems.size(); ++i) {
// All the edits are associated with the first memtable of this batch.
assert(i == 0 || mems[i]->GetEdits()->NumEntries() == 0);
mems[i]->flush_completed_ = true;
mems[i]->file_number_ = file_number;
}
// if some other thread is already committing, then return
Status s;
if (commit_in_progress_) {
TEST_SYNC_POINT("MemTableList::TryInstallMemtableFlushResults:InProgress");
return s;
}
// Only a single thread can be executing this piece of code
commit_in_progress_ = true;
// Retry until all completed flushes are committed. New flushes can finish
// while the current thread is writing manifest where mutex is released.
while (s.ok()) {
auto& memlist = current_->memlist_;
// The back is the oldest; if flush_completed_ is not set to it, it means
// that we were assigned a more recent memtable. The memtables' flushes must
// be recorded in manifest in order. A concurrent flush thread, who is
// assigned to flush the oldest memtable, will later wake up and does all
// the pending writes to manifest, in order.
if (memlist.empty() || !memlist.back()->flush_completed_) {
break;
}
// scan all memtables from the earliest, and commit those
// (in that order) that have finished flushing. Memtables
// are always committed in the order that they were created.
uint64_t batch_file_number = 0;
size_t batch_count = 0;
autovector<VersionEdit*> edit_list;
autovector<MemTable*> memtables_to_flush;
// enumerate from the last (earliest) element to see how many batch finished
for (auto it = memlist.rbegin(); it != memlist.rend(); ++it) {
MemTable* m = *it;
if (!m->flush_completed_) {
break;
}
if (it == memlist.rbegin() || batch_file_number != m->file_number_) {
batch_file_number = m->file_number_;
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit table #%" PRIu64 " started",
cfd->GetName().c_str(), m->file_number_);
edit_list.push_back(&m->edit_);
memtables_to_flush.push_back(m);
}
batch_count++;
}
// TODO(myabandeh): Not sure how batch_count could be 0 here.
if (batch_count > 0) {
if (vset->db_options()->allow_2pc) {
assert(edit_list.size() > 0);
// We piggyback the information of earliest log file to keep in the
// manifest entry for the last file flushed.
edit_list.back()->SetMinLogNumberToKeep(PrecomputeMinLogNumberToKeep(
vset, *cfd, edit_list, memtables_to_flush, prep_tracker));
}
// this can release and reacquire the mutex.
s = vset->LogAndApply(cfd, mutable_cf_options, edit_list, mu,
db_directory);
// we will be changing the version in the next code path,
// so we better create a new one, since versions are immutable
InstallNewVersion();
// All the later memtables that have the same filenum
// are part of the same batch. They can be committed now.
uint64_t mem_id = 1; // how many memtables have been flushed.
// commit new state only if the column family is NOT dropped.
// The reason is as follows (refer to
// ColumnFamilyTest.FlushAndDropRaceCondition).
// If the column family is dropped, then according to LogAndApply, its
// corresponding flush operation is NOT written to the MANIFEST. This
// means the DB is not aware of the L0 files generated from the flush.
// By committing the new state, we remove the memtable from the memtable
// list. Creating an iterator on this column family will not be able to
// read full data since the memtable is removed, and the DB is not aware
// of the L0 files, causing MergingIterator unable to build child
// iterators. RocksDB contract requires that the iterator can be created
// on a dropped column family, and we must be able to
// read full data as long as column family handle is not deleted, even if
// the column family is dropped.
if (s.ok() && !cfd->IsDropped()) { // commit new state
while (batch_count-- > 0) {
MemTable* m = current_->memlist_.back();
ROCKS_LOG_BUFFER(log_buffer, "[%s] Level-0 commit table #%" PRIu64
": memtable #%" PRIu64 " done",
cfd->GetName().c_str(), m->file_number_, mem_id);
assert(m->file_number_ > 0);
current_->Remove(m, to_delete);
++mem_id;
}
} else {
for (auto it = current_->memlist_.rbegin(); batch_count-- > 0; it++) {
MemTable* m = *it;
// commit failed. setup state so that we can flush again.
ROCKS_LOG_BUFFER(log_buffer, "Level-0 commit table #%" PRIu64
": memtable #%" PRIu64 " failed",
m->file_number_, mem_id);
m->flush_completed_ = false;
m->flush_in_progress_ = false;
m->edit_.Clear();
num_flush_not_started_++;
m->file_number_ = 0;
imm_flush_needed.store(true, std::memory_order_release);
++mem_id;
}
}
}
}
commit_in_progress_ = false;
return s;
}
// New memtables are inserted at the front of the list.
void MemTableList::Add(MemTable* m, autovector<MemTable*>* to_delete) {
assert(static_cast<int>(current_->memlist_.size()) >= num_flush_not_started_);
InstallNewVersion();
// this method is used to move mutable memtable into an immutable list.
// since mutable memtable is already refcounted by the DBImpl,
// and when moving to the imutable list we don't unref it,
// we don't have to ref the memtable here. we just take over the
// reference from the DBImpl.
current_->Add(m, to_delete);
m->MarkImmutable();
num_flush_not_started_++;
if (num_flush_not_started_ == 1) {
imm_flush_needed.store(true, std::memory_order_release);
}
}
// Returns an estimate of the number of bytes of data in use.
size_t MemTableList::ApproximateUnflushedMemTablesMemoryUsage() {
size_t total_size = 0;
for (auto& memtable : current_->memlist_) {
total_size += memtable->ApproximateMemoryUsage();
}
return total_size;
}
size_t MemTableList::ApproximateMemoryUsage() { return current_memory_usage_; }
uint64_t MemTableList::ApproximateOldestKeyTime() const {
if (!current_->memlist_.empty()) {
return current_->memlist_.back()->ApproximateOldestKeyTime();
}
return std::numeric_limits<uint64_t>::max();
}
void MemTableList::InstallNewVersion() {
if (current_->refs_ == 1) {
// we're the only one using the version, just keep using it
} else {
// somebody else holds the current version, we need to create new one
MemTableListVersion* version = current_;
current_ = new MemTableListVersion(&current_memory_usage_, current_);
current_->Ref();
version->Unref();
}
}
uint64_t MemTableList::PrecomputeMinLogContainingPrepSection(
const autovector<MemTable*>& memtables_to_flush) {
uint64_t min_log = 0;
for (auto& m : current_->memlist_) {
// Assume the list is very short, we can live with O(m*n). We can optimize
// if the performance has some problem.
bool should_skip = false;
for (MemTable* m_to_flush : memtables_to_flush) {
if (m == m_to_flush) {
should_skip = true;
break;
}
}
if (should_skip) {
continue;
}
auto log = m->GetMinLogContainingPrepSection();
if (log > 0 && (min_log == 0 || log < min_log)) {
min_log = log;
}
}
return min_log;
}
} // namespace rocksdb
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